text:
Is it possible to recover from a flat spin?
In Top Gun, Maverick's F-14 enters a flat spin after flying through another F-14's jetwash, forcing him to eject and causing the death of Goose.
Is this scenario possible or was it only created for theatrical purposes?
If not, how does it happen, and how can it be avoided, especially for other types of aircraft such as the B-2?

I know it's possible because I just did a quick search of the NTSB crash reports database and got a heck of a lot of results.  The real question is "can it be avoided and how".(Go here: http://www.ntsb.gov/aviationquery/ then go to the bottom and put "flat spin" into the string search box)

Sweet.  Really looking forward to some response to that.  Seems like it should vary by aircraft type.  For example, I wonder how a B-2 (with no vertical stabilizer) avoids flat spins and, if it were to enter one, how it would exit it.

Bob Hoover found a reliable way to recover from a flat spin: drop the landing gear and lower the flaps. It probably wouldn't work in every airplane though.

@Somebody smart -> http://www.piperowner.org/articles/close-calls/264-close-calls-surviving-a-flat .  That seemed to work for this pilot, how, why?

@flyingfisch - and as my last little pound on this dead horse, here's a very long discussion/argument on the subject on another forum: http://www.airliners.net/aviation-forums/tech_ops/read.main/169310/

Doesn't this answer it? Why not? http://en.wikipedia.org/wiki/Spin_(flight)#Entry_and_recovery and http://en.wikipedia.org/wiki/PARE_(aviation)

@GlenTheUdderboat that works for normal spins, but not flat spins ;-)

Since the question specifically mentions Top Gun and I just read about this unfortunate bit of history. Art Scholl, doing camera work for the movie, died after failing to recover from a flat spin. http://en.wikipedia.org/wiki/Art_Scholl

@orangewarp wow, that is really unfortunate...

Global Girl has some video of flat-spin training and recovery.

Every aircraft is different. Although I'm not sure why this is, I was educated in USAF pilot training aerodynamics, that the design properties that make an aircraft more susceptible to spinning also make it easier to recover from one - and vice versa. The F-4 Phantom was susceptible to a regular spin, and could recover from one, but if it entered a flat spin, the centrifugal forces were such that even if the drag chute was deployed, recovery was problematic.

The F-14 is special; to stop the flat spin you need to pull on the stick. Then the spin can be recovered from.
This is different from what you learn about regular spins, where pushing the stick would be a better recovery method. In a flat spin, the forward fuselage dominates the aerodynamic forces, and we all know there are no control surfaces which could influence this flow. Wings and horizontal surfaces are fully separated, and elevator deflection is mostly useless. As others have pointed out before, a flat spin can only be stopped by shifting the center of gravity forward or deploying a spin chute. The F-14 was an exception.
Spinning the F-14
Early on, the Navy lost several F-14s due to flat spins. They then studied the phenomenon at Pax River, and in the end Bill Bihrle found out that the elevator shields airflow from the two vertical tails of the F-14 when the stick is pushed, but moves out of the way when the stick is pulled full aft. You have to know that the elevator of the F-14 is a full-flying surface, and the movement range is from -20° to +70°. At +70° it is almost in line with the airflow in a flat spin, and now the vertical tails are no longer in the wake of the elevator. They now can reduce the high yaw rate, which in turn reduces the high pitch-up moment of the rotating fuselage. With the lower inertial pitch-up moment, the elevator then has to be moved back to neutral, and the drag from wing and elevator is enough to pitch the aircraft fully down and out of the spin.
Naturally stable flying wings never enter a flat spin; their spin modes are all fairly steep due to the lack of a strong inertial moment from the lengthwise distribution of masses.
Influence of mass distribution
I guess I now need to explain the inertial moment which causes the high pitch attitude in some aircraft. The axis of the spin rotation is close to the aircraft's nose, and the tail has the biggest distance from this axis. In a flat spin the axis of rotation is even more back, close to the center of gravity. All parts of the aircraft rotate with the same yaw rate, and the centrifugal force from this yawing motion grows linearly with distance from the spin axis. This difference in centrifugal force along the lengthwise coordinate of the aircraft pulls the aircraft in a near-horizontal attitude.
Watch this movie of the spinning XB-70 to get an idea how it looks. Depending on elevon settings, the spin axis is somewhere between the cockpit and the forward tip of the wing triangle. With the damaged configuration (watch without sound for no distraction) you get a typical flat spin with the spin axis close to the center of gravity since there are few suction forces acting on most surfaces - only drag and the nose vortex (more on that below) remain.
How to avoid flat spins
If you have a configuration which is prone to flat spins, you need to change the shape of the fuselage tip. A rotating fuselage tip at high angle of attack will produce vortices at its side, and the yawing moment of these vortices will grow stronger with increasing yawing motion. This is why a flat spin is self-stabilizing. One way to suppress these vortices is the placement of small spoiler strips along the nose (which fixes the vortex position and reduces this self-stabilizing effect), and another is to make the nose shape flatter.
Unfortunately, this can only be done long before take-off.
Answer to your question
Regarding the "Top Gun" scenario: If the F-14 is at high angle of attack and the jet wash hits it asymmetrically, the airplane could enter into a spin. But from there it is still some way to the fully developed flat spin, and I would expect that a skilled pilot could recover from this momentary upset.

At high AoA's if the 14's compressor stalled (or lost thrust) the plane would nearly instantly enter a flat spin which was generally irrecoverable.  Often a CG change was required to recover.  Here's a link to a discussion about F14 spins from guys that flew them. http://www.airwarriors.com/community/index.php?threads/tomcat-and-flat-spins.37474/

@SHAF: Asymmetric thrust would certainly help to quickly reach the high yaw rate necessary to stabilize a flat spin. I have most of my F-14 flat spin knowledge directly from Bill Bihrle, and both of us have never experienced it directly. I wouldn't mind if I had the chance, though, with enough altitude for recovery.

FWIW in case anyone cares, the EA-6B spin recovery procedure was also to pull stick full aft to clear airflow to the rudder.

Re "Naturally stable flying wings never enter a flat spin; their spin modes are all fairly steep due to the lack of a strong inertial moment from the lengthwise distribution of masses.". -- for some reason, hang gliders can be made to spin very flat, looks like a maple seed coming down.  In fact that is the only spin mode that can be sustained for more than one turn or so in these aircraft.  Pilot must keep body weight shifted full to one side to sustain the spin though.

I have recovered from a flat spin doing upset training in a Extra300L. Here's the video (you'll notice a secondary stall at 0:33 because I pulled too hard in the dive).
It's interesting to note how one enters such a spin: first you enter a regular spin, and let it develop fully, then you do everything wrong: add full power, pull back on the sick, and depress the "soft" rudder in the direction of the spin.
What happens is very interesting: the spin starts to accelerate as the point of rotation moves from somewhere in front of the nose, backwards until it's inside the plane and the nose is moving one way (EG port) and the tail moving the other (starboard). It rotates a few times per second.
The recovery was fairly standard in the Extra300L: just PARE, and you're out in a second (that feels like an hour)

5 year old post, perfect recovery, no comments!!!  Yes, the 300 is light and has a large rudder with area below the Hstab/elevator.  But notice the position of the cockpit canopy (further back) and more fuselage area behind the wings, which were fully symmetrical.  The XB-70 crash analysis video shows the wing tips down, creating (in the plane of the rotation) a heavily cambered surface.  Can these factors make a difference?

The key to recovering from a flat spin is partly in the aircraft's design (aerobatic aircraft are built to handle "flatter" spins than normal aircraft and recover more readily), partly in the loading (specifically the location of the center of gravity), and partly in how "flat" the spin actually is.
There is going to be a point for any aircraft where you simply don't have the control authority to recover though (absent something extreme like mounting JATO bottles to the wing and firing them opposite the direction of the spin to stop the rotation).
There are definitely instances where pilots have been able to recover from a flat spin though - one example being is the Piper Owner story Jay Carr pointed out. Aircraft can sometimes even recover on their own, such as the "cornfield bomber" which actually recovered itself after the pilot ejected.
I can't locate the article, but I recall early in my training reading a story about an instructor and student who entered an inadvertent spin while practicing stalls. The spin went flat, and they were only able to recover by literally climbing forward onto the glare shield to move the center of gravity far enough forward that the nose dropped and normal spin recovery procedures were effective.

As for avoiding flat spins, they're best avoided by avoiding spins entirely, and by applying prompt and correct recovery inputs if a spin is inadvertently entered (spins tend to "go flat" as they progress, so recovering early minimizes the risk of a "regular" spin going flat).
How easy that recovery is depends on the aircraft's loading (center of gravity) - as illustrated by the "climb onto the glare shield" example above.

During certification flights, aircraft manufacturers mount small parachutes to the outside of the airplane which can be used to recover from a spin if the "normal" methods don't work.  That's another way to escape one.  :-)

@Lnafziger Let's call that "The Cirrus method" :-)

I still wonder if a flying wing design would be more prone to a flat spin than a normal aircraft (what with the lack of vertical stabilizers). Didn't see anything in my searches, but it seems like it would be awful hard to avoid on during a stall.

@JayCarr I'd imagine that like with conventional aircraft it would depend on where the center of gravity falls relative to the center of lift - the goal is to get the "nose" down (reducing the angle of attack) and convert the flat spin into a conventional ("dive") spin from which you can recover. My real question for flying wings would be this: "How the heck do you recover something like this with no rudder?!" (How effective are the alternate yaw control systems in spins?)

@Lnafziger The Navy tried that and the test pilots had to eject

@SHAF That depends on the airplane, of course.

@Jay Carr see you are still around. Don't know if you ever got an answer about flying wings so I'll try.  It may be related to "spiral instability" incipient to the spin.  Planes with a long fuselage and large vertical tail area get a rotational "kick" when they slip sideways, which the stalled inner wing cannot counter act. The less stalled (or unstalled) outer wing then literally screws the plane into the ground.  Flying wings won't get this kick, additionally, the clamshell yaw controls would be what I wanted on any wing to get out of the spin along with rudder IMHO.

Every airplane type has it'd own unique way of spinning. It can happen to also have an irregular spin path with a partial flat spin.
In a flat spin, you almost have no authority on the controls, but the center of gravity (CoG) in a forward position (all planes are usually designed in that way) will convert the flat spin into a dive spin and so by gaining again authority on the rudder you can exit from the spin sooner.
It's the higher weight in the forward position together with gravity being the main cause of converting a flat spin into a dive spin. Most modern light planes are designed to automatically exit from a spin, even without any action from the pilot. It is also quite simple to exit a spin, but how varies from plane to plane. Usually, you put full rudder against the spin direction, push the stick slowly forward a bit and wait. Aerobatic planes enjoy doing spins without any extra risks compared to normal flight.
The real problem is the high loss of altitude while waiting to exit from the spin. The plane will have a high vertical speed, so the danger comes from if there isn't enough altitude at the start of spin. A spin while landing is usually deadly. With unlimited altitude, every plane mathematically would exit sooner or later from any kind of spin, simply due to air friction, but this is theory since altitude is always quite limited.
Another problem for spins, is that you may not realize that you are spinning at all and so take wrong actions.
Military jets are different. They are built to be dynamically unstable for better reactivity. I don't know much about them. Still, with a CoG in a forward position, they too, should convert a flat spin into a dive spin. The main problem is still enough altitude. A few rotations may be all you have before reaching the ground.
To intentionally enter a spin, you need low speed; it's a stall condition of only one wing, which will drop, starting an auto-rotation which then converts to a spin. All this can be easily avoided with enough speed. Even if the engines are dead, you can always glide to the ground at the speed you wish.

I took a CFI student for mandatory spin training in a Cessna 152 Aerobat. He did 3 spins to the right and recovered. After completing his 3 spins to the left the recovery procedure did not work so I told him to repeat. The second recovery also failed so I took the controls. The spin by this point had developed into a flat spin with the nose to the horizon and a much faster rotation than normal about the center of the aircraft and a very high descent rate. I too tried the recovery procedure to no avail.
Prior to the flight, the student taught me the spin recovery technique as if I were the student. Though I had heard "move the control wheel briskly forward" a thousand times, this time I pondered why "briskly" was so important. I remembered my ponderings in the midst of our flat spin, with the yoke all the way forward. I then brought the yoke back the the aft position and again threw it "briskly" forward. When I did, I noticed a slight rock in the aircraft's pitch. I repeated this, slamming the yoke all the way aft and forward again. Each time the plane rocked more and more. After doing this about 6 times, the aircraft rocked (pitched) far enough nose down to regain air flow over the rudder and allow for a recovery.
The student and I were extremely dizzy after spinning so fast for so long. The student was so shocked by the experience that he quit his flight training.
Back at the flight school I reported what happened. A mechanic told me that a flat spin can sometimes occur with the right amount of fuel in the tanks, somewhere around half full. He said that the initial spin can sling the fuel to the ends of the wings - that coupled with the rotation can create a sort of gyroscopic effect and force the plane into a flat spin. Not sure if that is true but it seemed plausible at the time because we had half tanks.
I do not claim this is the proper way to recover from a flat spin in any aircraft but at the time I had run out of options and this seems to have saved my life.

Honestly, a very moving story.  I have heard that rudder throw is limited on student aircraft.  DEFINITELY go back and ask that mechanic if that could be the case.  Fuel being slung around (half empty tanks) also sounds plausible.  But lack of rudder authority may also link with high speed aircraft flat spinning, as excessive rudder travel can't be designed in for fear of excessive side load on V stab.  Glad you got out of it ok!

This was just a stock C152 with no limitations imposed on rudder deflection (if that's what you mean). This happened 20 years ago so the mechanic is long gone.

A flat spin is a spin where, the aircraft is in a balanced state. It just spins round and around like a spinning top. It won't recover because the forces acting on the airplane are in equilibrium. Controls and engine power become completely ineffective.
Can it happen? Yes, depending on the airplane design and center of gravity. If CG is aft it's more likely.
How to avoid? To spin, you must first stall. Avoiding stalls and proper stall recovery procedures are ways to go.
My instructor, who was a military pilot, told us that one F-16 pilot entered a flat spin when he was playing around. He did not want to eject as the tapes would show that he lost a completely good aircraft on his own, not due to failures or accidents. He climbed out of the cockpit towards the nose. This upset the balance and tipped the nose down. He then climbed back and recovered the aircraft.

"...He climbed out of the cockpit towards the nose..." I just can't believe that last part, how would anyone be able to do something like that, open the canopy while in flight at several hundred knots, crawl towards the nose,... Sounds like a really bad action movie!

@kebs That's what we were told. In a flat spin the plane would be very slow, so it's not "several hundred knots". Still, it does sound crazy.

And I bet the aft-hinged canopy somehow magically did not got torn loose in the airflow either, so there was no evidence of the drama after landing--

I have only done flat spins in a Pitts S1.
The inverted ones are oscillatory with a lot of buffeting and control snatching, but recovery is quick (rudder not shielded by tail plane and elevator).
Upright flat spins are smooth and stable, rotation not that fast and sink rate comparatively low.
To enter, start with a normal left rudder power off spin.
After a turn, add full right aileron which flattens the attitude a fair bit and then add power.
The nose comes up to the horizon and the bank angle is about 25 deg to the left.
I watch the altimeter closely.
Power-off recovery apparently takes some time but I have not tried it as I use the technique described in Alan Cassidy’s book, Better Aerobatics.
Which is leaving the power on (the better airflow over the tail overcomes the nose-up gyroscopic effect of the left yaw); full opposite - Right- rudder then make sure the stick is in the rear, right corner, then move it to the left rear corner, then easing it forward while holding full left aileron.
The S1 stops very quickly after that, centralise and pull out.
Looking at the F4U with the cowls and panels off and seeing that huge R2800 so far forward, I was reminded of the Vought test pilot, Boone Guyton saying to another pilot “if you are thinking about spinning the Corsair, don’t”.
Rotating masses and Conservation of Angular Momentum etc. I wouldn’t spin anything without type specific instructions or good advice, but the Pitts S1 has all the masses close together, is well sorted and understood.
It is the most honest machine I have flown in 48 years.

Welcome to Av.SE, and thank you for an interesting description of a realm that most of us never enter!

I flew Harvards for 7 years (1961 to 1968) in Calgary (CYYC), doing Cloud Seeding (Hail-Suppression). The pre-modified MK2’s on occasion would go into a flat-spin. We didn’t practice it but were told to rock the AT6 nose up then down by applying full power and at the same time pull back all the way on the control column, then immediately push full forward on the control column at the same time as pulling power back to idle. Hopefully this would force the AT6 to get nose down to build up speed. Then recover to level flight.
They then rectified AT6 flat spins by adding lead weights to the motor-mounts which is ahead of the CofG. The MK4’s had the forward extra weight built in during manufacturing, which solved the problem. JH

Your answer is tangent to the question. Which is okay as a supporting information but it doesn't directly answer the question. iow instructions for an attempted recovery does not imply actual recovery.

The best recovery technique for a flat spin will vary from one aircraft to another.  I had a radio-controlled model airplane of a basically conventional high-wing design (but a fair bit of dihedral and no ailerons) that could be put into a very flat spin.  Recovery was ONLY possible if I applied power; rudder and elevator alone wouldn't do it.  In fact adding power would bring the plane out of the spin even if the rudder and elevator were kept centered.  Then I added ailerons to the wing and found that applying ailerons INTO the spin was also an effective recovery technique.  Again this technique was effective enough that it would effect recovery even if the rudder and elevator were kept centered.

Future edit: at a later date, I removed the dihedral from the wing and found the spin / spin recovery characteristics essentially unchanged.  Also note that adding power while holding full down elevator pitched the flight path down near vertical-- not good near the ground.

Flat spin is worst case scenario of pilot mistake and fatal for all types of aircrafts, except fighters, and with thrust to weight ratio of no less, than 0.72-0.75. Thus even military A10 will be lost if it happens, let alone any passenger aircraft. Modern aircrafts have CG moved to nose with massive engines though, and have a chance to move nose down, if at early stage of flat spin. If developed, and plane goes as falling leaf, or rotating stbilised,theres no chance to recover.

I mean, with equal thrust of both engines. With different ones, fighters with less thrust to weight ratio may seemigly be recovered,

No necessarily true.  Aerobatic category aircraft can routinely be placed into flat spins and recover from them.


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Raising flaps on touchdown in gusty conditions
In As the Pro Flies, John R. Hoyt writes (pages 41-42):

Suppose we have to land in high, gusty winds. That's what happened to
  Pilot Z, who once landed his plane during such conditions with his
  flaps down. After the wheels were on the runway he relaxed, never
  realizing that a plane is not landed until the switches are cut.
  Because he still had airspeed and because full flaps lowered the
  take-off speed, a small gust of wind was all that he needed to begin
  flying again. The additional lift was enough to raise him 10 feet from
  the runway, and at that point he ran out of gust, a condition aptly
  described as dis-gusted. He would have dropped back on the runway, had
  not an alert co-pilot opened the throttles and saved both the day and
  the landing gear.

He goes on to state how much flap should be used in what conditions, and then he finishes with this:

Let us then raise the flaps in gusty or crosswinds as soon as the
  wheels touch down. To wait until it is time to taxi doesn't help slow
  the plane very much, and flaps do constitute a hazard in gusts.
  Besides, it is surprising how much a small pebble costs when it goes
  through a flap.

Is he right? Should flaps be raised immediately after touchdown in gusty conditions?

related for normal conditions: http://aviation.stackexchange.com/questions/1189/raising-the-flaps-right-after-touchdown-good-or-bad?rq=1

I would say that this is covered pretty well in the above question, except for the "gusty conditions" part.  I'm not sure that it warrants its own question though, and you could ask for clarification on the answers there if that is the only difference in your question.

OK, I just didn't know how to do the quotes as well. I guess we can close it.

Also, in my mind, the problem that he described is that the pilot "quit flying the airplane", not that he landed with full flaps....

I was taught to use less flaps when landing in gusty/crosswind conditions for exactly this reason.  Per my POH, short fields call for reducing flaps on touchdown regardless of winds--but that's the only time I'd ever risk it.

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What is the advantage of the two-part rudder and how does it work?
I saw that some aircraft's rudder is composed of an upper rudder and a lower rudder (B727, A380, ...) as illustrated:

Image Source
I wonder how does it work compare to a normal rudder and what are the pros and cons of the two-parts rudder over the one-part rudder?

This is called Split Rudder and it provides redundancy. They run on different systems so if one fails, the other one can be used.
Here is a picture of a split rudder:

Split rudders also provide a finer high speed control, in that only the lower one moves at high speed, reducing the exposed surface area and therefore the control effect.
Very importantly, there is a structural benefit. When we use the rudder it imposes a twisting load on the vertical fin. By only using the lower rudder, when the aircraft is at high speed, we reduce the twisting moment and transfer that load to a bigger, stronger, part of the airframe. The principle is the same as why the outboard ailerons are disabled at high speed.
The patent information is here.

To add a little context, in case a reader misses the significance... The rudder is the only control surface for which an aircraft only has one. Almost all aircraft have two sets of flaps, ailerons, elevators etc... Although it's possible to fly most aircraft without a rudder (or other control surface), it's not a comfortable experience and a split rudder makes this situation less likely.

@JonStory In case of twin tail airplanes, there are two rudders.

Very true, I'll concede that point although I'll counter that there aren't too many twin tail aircraft around. Worth noting next time you're in a P-38 Lightning though :p

Seems surprising that you can get a patent (filed in 1995!) for a split rudder design. Seems so basic and so obvious. Of course, the patent system is broken but still...

I've been a huge fan of planes since I was about 9 years old, , 13 years later and until now I had never ever ever heard of or seen a split rudder before!

As pointed out by Farhan, it adds redundancy to the aircraft.
A 747 once experienced a rudder hard over. Even with the split rudder design, the crew had to rely on asymmetrical thrust to control the aircraft. If it had one very large rudder surface, control would be much more difficult, or may even be impossible.

As, indeed, happened with a number of 737s in the 1990s - the 737, unlike the 747, has only one rudder, and at least two fatal crashes were caused by that single rudder going hardover.

It allows one part to jam while the pilot retains control over the other part.
Also the higher portion of the rudder induces roll when deflected, at high speeds (where control surface deflection is more effective) only the lower portion can be deflected to minimize this effect.

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Is it possible to go-around at Lukla Airport?
On this airport, it seems the runway end with a wall followed by a mountains. Thus the pilots physically can't overrun the runway and if they decide to interrupt the landing, the go-around maneuver seems to include a very tight turn to avoid the mountain unless performed very soon during the approach. Is it possible to perform a go-around, and a which point it becomes impossible for this particular airport?

No, it is almost impossible.
The only runway (06/24) Lukla Airport is just 1500 feet long. This article lists some interesting facts:

The topography of the place makes any go-around impossible. At the
  south, the runway is the end of an angled drop of about 2000 feet.
  This cliff is fenced off as a precautionary measure. At the northern
  end of the runway there is a huge mountain terrain. It leaves no room
  for error.

A pilot mentions the same here:

"Because there is no way to go around again, we have to calculate many
  things like air speed, tail wind, fog. If you don't do the proper
  calculation or proper exercise, then it (an accident) happens."

Planes land on runway 06 (Heading 060 or ENE) and takeoff from runway 24 (Heading 240 or WSW). This picture shows the cliff on North:

There have been several accidents at this airport.

Please be a bit more specific.  What kind of plane are you asking about?  Helicopter?  What is a go around (i.e., the pilot can make the decision to divert and go elsewhere.  At what distance do you consider that to be a go around and not just a diversion?)  To get a good answer to an interesting question, you need a bit more specificity.

@SkipMiller It appears that OP is familiar with most of the clarifications you are asking. Mostly airplanes land on that airport. If we talk about go-around vs diversion, I feel that it would become off topic on this thread. Thanks.

Agreed with @farhan - the question is clearly regarding a go around (ie an aborted landing while on approach) rather than a diversion.

This is not quite correct - it is possible to go-around at Lukla. I've seen it done. That said, by the time you realise you need to go-around it's often too late, the tricky bit is just before the threshold (lots of shear there) and your options are very limited at that point.

@sp1 I said the same thing. You just reworded my premise and down voted.

Your response doesn't even make a mention of go-arounds.

Hi guys few days ago a twin otter did make an aborted landing and made a "go around" at the airport and headed back to Kathmandu. This is the first time such an incident happened although there has been numerous crashes in the past.
Here is a link to the video.

Scary move! Back to Kathmandu for a change of underwear.

That's a flight delay I'd be happy to accept. Yikes!!

If you do a search on youtube you will find several video on go arounds at this airport, so I think go arounds are more common than some of the respondents above indicate.

This is more of a comment than an answer.  Once you gain enough reputation, you will be able to comment on any post.

I disagree with the comments. This is very much an answer, even if it is a short one and not very well documented

You can not go around at Lukla, but if you try super hard, with a bit of luck, you might be able to turn back. But it wouldn't look like a normal go around. The reason for this is because Lukla is right in front of a huge mountain, And you won't have enough speed to climb fast enough.

I fail to see what this answer brings that is not already in other answers.


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Can small children be seated away from their parents/guardians on a flight?
I am interested if there is any law or regulation which prohibits carriers from seating children in a seat not adjacent to their parent/guardian?
I am flying with a group of 17, which includes 2 infants (without allocated seats), but seven children ranging in age from 2-5. We opted not to pay the extra charge to pre-allocate seats, and the airline has allocated us seats spread around the aircraft in a configuration which does not allow an accompanying adult to sit next to a child.
I was sure there was some air law which prohibited this on safety grounds, but have been unable to find it.
This question relates to the EU, but answers regarding other jurisdictions welcome.

I always thought paid or unpaid seat pre-allocation was not guaranteed anyway, and could be overidden at checkin if other important requirements arose? In the past I've found that if you turn up early to the check in counter the staff will often be able to help you out.

This doesn't seem to be related to aviation, but to travel and airlines. I suggest to move this (old) question to Travel.SE.

@mins - Im happy with whatever fits the community, although at the time I was interested in this not from the "travel and tourism" slant, but the aviation regulation and/or law POV.

This is what I could find. I looked on the Civil Aviation Authority's website and found this article.
Seating Allocation

Families, children and infants
The seating of children close by their parents or guardians should be
  the aim of airline seat allocation procedures for family groups and
  large parties of children.
Young children and infants who are accompanied by adults, should
  ideally be seated in the same seat row as the adult. Children and
  accompanying adults should not be separated by more than one aisle.
  Where this is not possible, children should be separated by no more
  than one seat row from accompanying adults. This is because the speed
  of an emergency evacuation may be affected by adults trying to reach
  their children.
Whenever a number of infants and children are travelling together the
  airline should make every effort to ensure that they can be readily
  supervised by the responsible accompanying adults.

From what I read, it doesn't look like there is a law set in stone, but instead it is recommended by the CAA to be put in regular practice by airlines.
If there was a law then Ryanair would have been in serious trouble for charging people extra  money to sit next to their kids.
Ryannair booking separates mum and tot

Thank you. Amazingly quoting this CAA recommendation to the airline made them "magically" find a whole extra row in the aircraft. Maybe they bolted an extension on.

I don't think there a "law", but the flight staff would prefer that.
When my children were young, they sometimes ended up separated from us. Usually they were just a row or two away from us. On several occasions the cabin personnel arrange with kind passengers to switch seats so my two children could at least be seated together.

Although there is not a rule about that, but since you are in a large group with many children, you may call the airline directly to see if they can make a special seat arrangement. Usually, they would do so.

Normal airline, sure. But those let you choose seats in the first place. Low-cost? Not likely; they want you to pay the extra for choosing seats.


text:
Why do large aircraft have their engines mostly on the wings, while smaller ones tend to have them in the tail or the tip?
Large passenger planes almost always have their engines hanging from the wings, Fighters usually have them in the rear, and small Cessnas have them on the nose.
What is the reason for these variations in design?

Many older jets like Sud Caravelle, DC-9 and B727 had engines on the tail and smaller jets (like the CRJ-200/700/900/1000 series) still do.

The DC-10, MD-11, and L-1011 have both (1 in the tail and 1 under each wing.)

or the BN Trilander... 1 prop in the tail, 1 in each wing...

Fighter engines are not in the rear. The exhaust nozzles are at the rear, but the engines occupy a region along the body. The main mass of the engine(s) is/are going to be pretty close the the aircraft's over-all CG.

Small aircraft need very low mounted wings to allow for a decent cabin height. The last commercial airliner which required the passengers to climb over the wing spar on their way to their seat was the Boeing P-247. Low wings do not allow the necessary space for engines, so the next best location is on the rear fuselage. Also, small aircraft have a relatively short fuselage, and the gear can be made short (and light) without risking a tail strike on rotation.
Fighters need to have small moments of inertia, especially in roll, so they cannot afford to put engines on the wings. Even the Me-262 was initially planned with fuselage-mounted engines, that's why it had this peculiar triangular fuselage cross section. Only when the engines grew in diameter during development they had to be placed on the wing.
Pros of rear-mounted / fuselage-mounted engines:

The wing is clean, having low drag and optimum conditions for lift creation.
The engines are easy to access (if mounted at the rear fuselage. Different story with buried engines!).
Smaller vertical tail needed for asymmetric thrust conditions.
Shorter, lighter landing gear possible (if rotation capability is not compromised).
Low roll inertia.

Cons of rear-mounted / fuselage-mounted engines:

No bending relief for the wing; heavier wing spar needed.
No help in flutter supression (a mass ahead of the elastic line helps).
Possible interference with wing wake at high angle of attack.
Forces the tail to be a T-tail configuration.
More structure needed to carry the thrust forces forward.
Intake noise is more audible, especially for passengers in the rear seats.

This picture of a Cessna Citation X should illustrate the point nicely.

I learned from this page that the Boeing 737 was initially planned with rear-mounted engines, like the Sud-Aviation Caravelle, which it was meant to replace. By selecting the final version with wing-mounted engines in the underslung design, Boeing could reduce the empty weight of the 733-100 by 700 pounds, no mean feat!

you could make a high wing airliner and have the engines hang under the wing. Think ARJ. Or a low wing airliner and have the engines on top of the wing. Think VFW614. And then there's the Comet, engines in the wing root.

@jwentig: Yes, you could, but it would not be prudent. The ARJ was initially a military transport, that's why it looks like one. And without Moritz Sutter, who wanted so dearly to have four-engined airplanes in Crossair, the commercial success would also have not been so great. At Crossair, the 146 had the nickname "Jumbolino".

The ARJ was developed from the 146, which was designed for the civilian market. The 146STA (I think it was called) was created as a military transport to create extra business, it wasn't the military version that was the initial concept (I may still have a 1980s era marketing brochure for that one I picked up at Farnborough some year).

Do you mean the wings are usually just one big structure instead of two separated ones ?

@Antzi: Yes, the center part is the heaviest section of a wing. Seeing a wing as two separate things sticking out at the sides will make you forget what is hidden inside the fuselage.

When designing an aircraft one basic factor is the thrust needed. In order to meet the requirements in power one or more engines are used. Factors that affect the selection are overall engine size, performance, efficiency, cost, material and thermal limitations during operation conditions like take-off, max continuous, max climb and max cruise. The installation has to be made with the lowest possible weight, drag and cost.
The positioning is indicated by aerodynamic factors such as drag, aircraft performance and manoeuvrability -pitching moments change around the center of gravity- and airflow through the engine, structural and purely functional/safety like debris injection inside the engine during landing or takeoff. All the above is just to give you a small taste of how the procedure goes.
In general, selecting the correct engine or combination of engines and the optimal positioning is a quite complicated and sometimes very tedious process.
However simply put, the amount of thrust -taking into consideration the minimum and maximum required for certification, performance etc- is split among the engines. Now let's address each type of aircraft in your question individually and try to make the logic behind the positioning:
Fighters:
These don't have the engines in the rear (e.g. they don't have pusher props), usually the jets are either underneath the fuselage like the Eurofighter Typhoon, incorporated to the fuselage, or the cockpit sits ontop of the jet nacelle like the Corsair II while in all cases the output nozzle is at the rear. The reasoning behind this positioning is the need for power and high speed. Apart that the fuselage is the only place where the engines won't hinder the mounting of missiles and other ammunition on the wings where they can be placed, inspected and replaced on demand and with ease.
Large passenger jets (like the Boeing 747):
The main characteristic of this type is that the space in the fuselage is needed for the passengers' accomodation. This alone rules out the incorporation of the engine in the fuselage as was the case in the fighters. The total weight increases leading to a need in power. The latter dictates either a very large single engine or more smaller ones -which is usually the case- that have to be distributed around the body which makes it logical to be put under the wings.
Medium/Small passenger jets (like the Cessna Citation Mustang or Dassault Falcon 900):
When the aircraft becomes smaller and the clearence of the wings from the ground becomes smaller the engines cannot be mounted under the wings without practical problems. So the engines move towards the tail where the fuselage needs to be reinforced to support the additional weight. The overall performance of the aircraft is different than that of a wing-mounted-engine aircraft because the cg is moved aft when it is empty.
Small Cessnas and others have a single engine in the nose because, as by now should be obvious, they need the power that can be provided by that single engine and for reasons of symmetry and construction costs.
All the above is a brief attempt to demonstrate the general thought process behind the positioning of the engines. Each way has it's pros and cons that every engineer takes into consideration and although these are the general configurations exceptions do exist. Some are this asymetric BV 141, or this DC-10 that has both wing and rear mounted engines.
Further reading here.

Most fighters do locate the engines themselves far aft. There's a lot of complex intake geometry occupying the rest of the space, something that's important in supersonic flight (dealing with shock waves, etc. before they get to the compressor). In some older passenger jets, such as the DH Comet, the jet engines were buried in the wing root. That must have made for some interesting structural design considerations!

Or above the wings, ala the Honda. :)

@PhilPerry I imagine engine maintenance or replacement was an afterthought on the DH Comet. Probably took a good salesperson to get airliners to overlook that fatal flaw.

@IceArdor it was a more aesthetically pleasing design though, but engine placement was the least of their problems.

@memoryofadream: To be fair, the later Comets did solve the problem the early models had with spontaneously falling apart in midair...

Also the nose-up moment during acceleration and likewise nose-down moment during deceleration with an under-wing engine design are favourable for stable flight characteristics. (the center of gravity is located in front of the center of pressure)
Airplanes with tail engines behave the other way around: during acceleration they produce a nose-down moment around their lateral axis. This in turn causes more drag and eventually more money. During deceleration, the nose-up moment can be dangerous, considering a near stall situation or slow flight in general.

Mostly because of the number of engines. If you have more than one engine then it gets hard to put both in the middle. It can be done, there are fighters with two engines in the middle, but it makes more sense (less noise, easier maintenance, etc) to put them in the wings.
There's also a weight advantage. The wings lift the plane, the engines are a major weight component of the aircraft. So if the weight is where the lift is being produced you don't need to reinforce the structure to carry the forces around. Hence lighter structure.

Vickers VC-10 and Illyushin Il-62 had four engines in the back. This worked well - but the wing was indeed heavier.

@PeterKämpf: And it also increases the likelihood of an exploding engine taking out the next engine over.

If you have one engine, it pretty much has to be on the centerline.  Otherwise, you'd have asymmetric thrust and you'd have to deflect the rudder, all the time, to maintain straight flight.  This causes drag.  Put it on the front, in a "tractor" configuration.  Or on the back, in a "pusher" configuration.  Or on top (see Lake Buchaneer/Renegade).  Either way, put it on the centerline of the aircraft.
If you have two or three engines,  you usually want those as close to the centerline as possible.  In the event that one of the engines shuts down (intentionally or otherwise), you want the remaining thrust to be as close to symmetric as possible, for the above reason.  Bill Lear was fond of saying that, in a twin-engine aircraft, each engine was just powerful enough to get you to the scene of the crash.  Meaning that, for many twin-engine aircraft, if you lost one engine, the other engine could keep you airborne until you could no longer counter the asymmetric thrust and you lost control and crashed.  This why Lear Jets all have fuselage mounted engines (as close to the centerline as possible) and the last airplane he was developing (the Lear Fan) had twin turboprop engines driving only one prop.  If you lost one of the engines in THAT bird, you had less power but your thrust was still perfectly symmetric.
There are aircraft which have > 3 engines, mounted close to the fuselage.  The Lockheed JetStar comes to mind, as does the Comet.  Unfortunately, putting multiple jet engines next to each other causes problems with the airflow around the air intakes, which can reduce the efficiency of the engines.
In the meantime, you also have the issue of weight.  Aircraft are designed so that the center of gravity (or center of mass, if you prefer) is on the wings because that's where the lift is.  One of the heaviest things a modern jetliner is carrying is ... fuel.  Not surprisingly, many of them have most of their fuel storage in their wings.  Another of the heaviest things they're carrying is ... the engines.  If you put the engines on the wings you have to have a significant-sized fin and rudder to keep it straight in an engine-out situation, but the forward-aft weight balance works out nicely.  Putting all that weight on the wings also means that the rest of the fuselage is bearing less of a load, which means the structure can be, relatively, lighter.
So, for large jetliners with massive high-bypass turbofans, you want the intakes spaced out as much as possible, for maximum efficiency, and you want them close to the wings so that much of the weight and the lift are easily connected.  Of course, being able to use gravity to drain fuel down, from the wings into the engines, also means the engines are more likely to get fuel if there's an electrical problems (which could shut down the fuel boost pumps).

Putting multiple jet engines next to each other can also cause problems if one of the engines blows up for some reason (it's much easier for fragments of one engine to disable another engine if said other engine is right next to the exploded engine); the Il-62 had a couple of crashes where this happened (admittedly, what actually caused the planes to crash those times was other engine fragments which punctured the fuselage and severed the control cables contained therein, but one can still see how the ease of engine fratricide could potentially cause problems all on its own).


text:
How do Ram Air Turbines get deployed?
I understand that most larger jets have a Ram Air Turbine (RAT) in case of total electrical failure (for instance, when you run out of fuel) in order to at least have some hydraulics and a couple of instruments. The RAT gets deployed automatically at the loss of electrical systems.
But how does it get deployed? I'm interested in the triggering mechanism, as, during a complete electrical failure, there can be no electrical trigger (computer or otherwise). So it must be something mechanical. Or are they relying on batteries?
I figured it'd have to be some failsafe mechanism, like stored (hydraulic or otherwise) pressure held back by something like an electromagnet or hydraulic pressure, cut the power and presto, the RAT deploys. However, I've never seen one deployed on an aircraft sitting on the ground with the power off, so that kind of shot down that idea.

The RAT is automatically deployed on many aircraft, including the CRJ and A320 series, but it can be manually released as well. In between the loss of power and the RAT spins up you have the batteries to fall back to which are normally fully charged.
The Airbus Manual has the following comment on the APU:

In case of total loss of all main generators, the RAT is automatically
extended and drives the emergency generator via a hydraulic motor. The
EMER GEN supplies the AC ESS BUS and the DC ESS BUS via the ESS TR.
The ECAM WD remains powered, with associated procedures presented.
Alternate law is operative through ELAC 1 and SEC 1
(Source)

While this is for the CRJ, who call it an Air Driven Generator (ADG):

In the event of a complete AC power failure in flight, the ADG will
automatically deploy and supply emergency AC power to the ADG bus and
to the AC essential bus. If the automatic deploy function fails, the
ADG can be deployed manually by pulling the ADG manual release handle
on the ADG CONTROL control panel at the rear of the center console.
(Source)

A RAT, with the spring loaded actuator visible:

I think most if not all are spring loaded, and have a little help from gravity on the way. You'll also notice that many are stored to be pushed into place by the jetstream.
Have a look at this video below around 0:20. The slow upwards motion suggests that it's having to reload the spring energy at 1:20. The doors are attached mechanically.
Taking a look at the Airbus Electrical System:

As can be seen, there's a hierarchy to electrical power use, and the battery feeds the essential busses, where the RAT deployment would be included. If I'm not mistaken, power is very limited: You loose some of the more fancy control computers along with the non-necessary stuff, like the copilot's displays, as can be seen in the following video.
Bear in mind that some aircraft, such as the 747 (up to -400), do not have a RAT on the aircraft, and rely on the windmilling engines to provide sufficient hydraulics to control the aircraft, and as such there's no deployment of sorts necessary.

Neat point about the wind-milling engines, didn't think of that.

Wow! I didn't know the 747 doesn't have a RAT! But why isn't it included for redundancy? British Airways Flight 9 comes to mind: http://en.wikipedia.org/wiki/British_Airways_Flight_9

@shortstheory BA9 did have a RAT- 4 windmilling engines :) note that the new 747-8i does have a RAT however, but none before that. since all the controls are hydraulic and it's fly by cable, i think you get away without the electricity for as long as it would be able to remain airborne.

Thanks! Is the 748-I/F a fly-by-wire plane or does it use the same control architecture as the 744?

But how does it get deployed? I'm interested in the triggering mechanism, as, during a complete electrical failure, there can be no electrical trigger (computer or otherwise).

Think the other way: it is not difficult to create a mechanism which deploys mechanically when there is no voltage.

On powering on plane's circuitry a latch withholding the RAT device is retracted and since then the device is hold retracted only by magnetic force of electrically powered coil which is stronger than loaded spring.
If the voltage drops unexpectedly, the coil loses its effect and loaded spring pushes the device out.
On regular powering of plane's circuitry off, latch for keeping the RAT device retracted when there is no electricity is shifted back into its place.

I am unable to get any actual blueprints but I tried to show you that moving something when a voltage is gone is not necessary a difficult mechanical engineering task.

But how does it get deployed?
NORMAL:  RAT is retracted (by manual cranking or by electric motor), against heavy spring bungee force and locked in faired position.
EMERGENCY:  RAT is unlocked and the spring bungee extends the RAT in to airstream.


text:
Can you fly a light GA airplane into a major hub? What operational considerations are there if you do?
I did my training around the Seattle area, and was told that landing at SeaTac Airport (the region's major International/Commercial airport), while not strictly forbidden, was definitely frowned upon because it can slow down and interfere with the big planes on schedules. To discourage GA aircraft from using the big airport, they have a variety of landing fees, ramp fees, and prior-approval requirements.
But later, I moved near MCI, and was told that landing at the big airport was no big deal.  That they're actually happy to have little planes there.
If you fly small GA planes, do you land at the major airports in your area?
What advanced preparations can you make to minimize your impact on the "big boys", and remain a good airspace citizen?

Note that the landing fees can vary from "Pretty darn reasonable" to "Doctor, he's in Sticker Shock!" depending on when you land and where you go on the airport. Take for example JFK's schedule of charges which aren't at all unreasonable unless you fly in during peak times or want to park / sit on the ramp for a long time.

You can always call on the phone to the FBO you intend to stop at and ask about any landing or security fees, and the 100LL fuel price.  Those amounts can usually tell you how much they like/dislike small aircraft.

Can you?  Absolutely, and air traffic control will treat you (almost) like any other airplane.  You are supposedly handled on a first-come-first-serve basis (reality is slightly different with different aircraft speeds, etc.).  Do the airlines like it if you slow them down?  No, but it's part of the system and the way that it works.
Very often, there are multiple runways at bigger airports, and sometimes there are even shorter runways that are dedicated for airplanes that don't need to land on the same one as the "big boys".  Even if not, they will work you in.
Now, that being said, very often there is a better option.  As you said, there are usually high fees at the big airports, so landing at a smaller satellite airport can often save you money and save you time because you won't have to taxi as far or sit and wait in line to get out.  An extra 15 minutes by car can be better than an extra 30 minutes while taxiing.
As far as being prepared, it isn't really much different than smaller airports other than the fact that ATC is much busier.  They don't have the time/tolerance to keep repeating instructions to you, and expect you to be "on your game".  When they rattle off taxi instructions like "Cessna N1234, taxi to the ramp via Alpha, Tango, Echo, and Xray. Hold short of runway 23." they expect a quick readback and for you to follow instructions exactly because they need to move on to the next guy.
It will also help everyone out if you don't fly your final approach the way that most people are taught for an entire 10 mile final:  very close to your actual landing speed.  In fact, you are usually landing on a runway that is 4X+ the distance that you need and you can slow down fairly quickly (especially compared to a jet), so if you can fly an extra 20 (or 80) knots as long as possible, it will be greatly appreciated and keep traffic moving.  Make sure that you leave yourself enough time to slow down at the end and above all else, be safe.

This is almost exactly my personal experience flying into KPDX a couple dozen times. Approach control doesn't mind you, doesn't make you wait, but does expect you to be professional on the radio and fast on final. It was a good long trip for the sharp instrument students finishing up their ratings.

@egid One time I flew into PDX and they thought my call sign was "citation" not "cessna" LOL.  But apart from that, they are very nice to deal with.  I'm sure they get a lot of Hillsboro Aviation Academy traffic passing through.

Flew into KMDW on my IFR cross country.  Not as bad as KORD would have been, but still very busy.  Glad I did it then when I was on top of my game.  That entire airspace is a demanding environment.  Actually landing (and doing a last minute side step for jet coming in behind us) was uneventful (albeit flown much faster than one would normally do at a small airport) compared to getting to the airport.  :-)

My favourite entry in my logbook is 2013-08-02 KOSH-KORD 1.5 hrs – from Air Venture in Oshkosh straight into Chicago O'Hare, in a Cessna 172 :-)
A friend of mine and I have flown into SFO (with our instructor), and dropped of my friend, who then took a Lufthansa flight to Munich.
So, having flown into SFO, ORD, and SAN (San Diego, the busiest single-runway airport in the US) in a Cessna 172, all VFR, here my observations:

obviously, prepare. I normally call the FBO, and maybe even the tower, just to get their input, and ask what would be a good time of the day.
best to fly with a fellow pilot, to share the workload.
have a taxi diagram at hand and familiarise yourself with it... navigation on the ground is harder than following the instructions in the air at some of these airports!
be prepared to wait outside class B for quite a bit, until they can work you in (and, be prepared to go somewhere else if they can't).
I like to think that they're the more likely to squeeze you in the more "professional" you are (radio calls, following their instructions quickly and precisely, etc.)
be prepared to be handed off from one frequency to the other for quite a bit.
out of courtesy, I try to go in pretty fast (fast for a C172, that is). The runways are long, so I've been on final with 120+ knots (and yes, that was a no-flap landing!)
ask the FBO about how much fuel you have to buy to get fees waived, and keep in mind that it's most likely going to be rather expensive... on a related note, in my experience the FBOs encourage you to come in, but then, they have nothing to lose: if you show up, they'll sell you overpriced fuel and charge you some fees; if ATC turns you away, they don't really care. That's why I like to talk to someone on the ATC side as well, or flight instructors at nearby GA airports.
review the radio sequence for departure, typically they want you to speak to Clearance Delivery before you talk to Ground
in my limited experience, ATC has been fast and professional in their communication, yet super helpful and friendly.
personally, I think it's super fun, and an awesome privilege, and I'm grateful that it is possible in the US. I've only done it rarely, and would not want to abuse this privilege - if every Cessna single engine out there attempted to land in a major hub daily, the privilege would be curtailed rather quickly, I imagine
it's just great to hear Ground say to you, "see the United 737 in front? Follow it until you see X-ray 3 on your left". Even better to hear Tower say "Lufthansa 123 heavy, hold short of Runway 27 left, traffic on final", and hear a reply "Hold short 27 left, traffic in sight (chuckling), Lufthansa 123", while you float over the numbers past a giant Lufthansa 747 :-)

Good advice!  One thing that I would point out is that they can only turn you away if you are VFR.  IFR arrivals are all treated the same (more or less).

“Hold short 27 left, traffic in sight (chuckling), Lufthansa 123” love it!

You wrote, "typically they want you to speak to Clearance Delivery before you talk to Ground".  If I'm going VFR, what am I suppose to say to C.D.?

@abelenky That would be a good separate question. Summary answer: 1. Establish two-way communication. 2. Say intent. They will often give you a squawk code and then a frequency for contacting Ground Control.

By the way, that runway above in the pictures (with the the LH 747 holding for our little Cessna 172) is SFO 28 L (same one that the Asiana flight 214 crash-landed on).

Note that SFO's landing fee is around $650 or more now with no exception for light aircraft. Basically the "go away price". No AVGAS either. But if I wanted to do it for my bucket list I'd call the tower and ask when it would be convenient to do a touch-and-go.

Just to add to Lnafziger's answer (which is entirely correct), the FAA has designated five airports as "High Density Traffic Airports" (covered in FAR Part 93 Subpart K) which specifically limit the number of scheduled IFR arrivals, and it's easy to misread that as "you can't land here."
Part 93.129 specifically says:

(a) IFR. The operator of an aircraft
  may take off or land the aircraft under
  IFR at a designated high density traffic
  airport without regard to the maximum
  number of operations allocated
  for that airport if the operation is not
  a scheduled operation to or from a high
  density airport and he obtains a departure
  or arrival reservation, as appropriate,
  from ATC. The reservation is
  granted by ATC whenever the aircraft
  may be accommodated without significant
  additional delay to the operations
  allocated for the airport for which the
  reservations is requested.

An almost identical exemption for VFR is listed in paragraph (b).
So they're essentially giving you a heads up that ATC can simply turn you away, and will likely do so during peak operation periods. However, during off hours (including hours when High Density rules are not in effect), there is no reason you can't land at even the biggest of [civilian] airports in the US.
High Density Airports currently include Laguardia (KLGA), John F. Kennedy (KJFK), Newark (KEWR), Reagan National (KDCA), and O'Hare (KORD).
Exceptions...
LGA and DCA require a slot reservation during most hours for unscheduled operations through the e-CVRS system.
In addition, DCA has very strict requirements which allow for only 48 GA flights each day. Among the requirements:

TSA Approved Armed guard on board.
No changes to the passenger manifest 24 hours prior to the flight.
TSA inspection of aircraft and passengers at a gateway airport prior to arrival.

See the whole list on the TSA's website.
And don't forget, the Washington, DC area has special flight rules in general. In other words, don't ever expect to land at DCA unless you have a really good reason.

I used to fly into LGA all of the time, and as long as you plan ahead, it isn't usually a problem to get one.  They aren't even that particular about the times, so if you have late passengers they don't normally turn you away as long as you have one, even if it falls outside of your reservation time.

Your TSA links are dead :(

Must be an American thing to allow GA to land at major airports.
Elsewhere in the world it's pretty much banned.   For example if you read the AIP sheet for Heathrow it says "Flights for recreational, commemorative, charity and record breaking purposes, light twin engined private aircraft and all light single engined aircraft will not be permitted to use the airport."
Elsewhere in the world, airports also tend to be located in class A airspace, which are IFR only and not open to VFR traffic.  So most PPLs without an IR rating would not be able to get anywhere near the airport anyway.

Class B airspace, in the US. Class A is way up in the sky in most parts of the world. ;-)

And in the US, Class A (FL180 to FL600) is the only one that's IFR-only.
That would suck to have airports under such strict control. It would seriously hamper General Aviation. Most airports in the US aren't under any sort of control and pretty much all are open to general aviation aircraft. Other than a few exceptions, I believe it's the same in most of the rest of the world, too.

I think Heathrow is an exception. Most major European airports allow any IFR flight, even if it's a tiny Cessna 172. VFR is another story though.

Heathrow is an exception to everything.  It's the world's third busiest airport and has only two runways.  Plus London has 5 other big international airports and many smaller airports. CDG would be a better example

Piper PA28 landing at LEMD https://www.youtube.com/watch?v=sifrXpIomFE

Re: Class B airspace, in the US. Class A is way up in the sky Wrong !  In Europe and elsewhere in the world, class A can be at any level.... from ground upwards.   E.g. coming back to my Heathrow example, the London and Heathrow TMA starts at SFC (i.e. surface) and goes up to whatever altitude it is.

Re: It would seriously hamper General Aviation.  ... lots of things hamper GA in the rest of the world, for the start, the lack of cheap gas that the Americans have.

@ColinPickard It's actually not the 3rd busiest by movements. It's 'only' 10th by movements. It was the 3rd busiest by number of passengers last year, but that's not particularly relevant for air traffic purposes. The U.S. has 8 airports that have more movements than Heathrow and China also has one.

@JohnDoe From a quick search, it looks like the U.K. is among only a few nations that use Class A airspace in terminal areas. Most other nations appear to use it like the U.S. (all traffic above a certain altitude) or not at all.

There are other airports with more movements, more runways, more passengers etc: the problem with Heathrow is simply that it's full: you simply can't fit more landing/takeoffs in there without compromising safety.

The big difference is that America has very low taxes on fuel compared to most of the rest of the world.

You can land anywhere you want, pretty much.  It all depends, as others have said, on how much of a landing fee you are willing to pay.
In some cases a large major airport really IS most convenient.  My wife and I wanted to visit the Udvar Hazy Air and Space museum during its grand opening in late 2003.  Dulles was still under the ridiculously strict DC ADIZ brought about as a result of an overreaction to 9/11.
But the process was well documented by then so we took off from KSNC (Chester) and headed south.  I picked up Flight Following just south of Newark.  (They tend to vector VFR aircraft out to sea in the Newark area, so I just fly over the Class Bravo.
At some point we were cleared into the ADIZ and were handed off from center to Dulles approach.  The approach controller set me up for a loooong base leg that would roll me out on a 2 or 3 mile final.  Which made sense.  There was no point in putting me in the long procession of commercial aircraft stacked up on 40 mile finals.
About 20 miles out, approach called me and asked if I could give them 160 knots.  (I flew an RV4, which was a 175 knot aircraft, but had a very low flap speed of 90 knots).  I agreed and pushed the throttle in.  A couple of minutes later, I got a request for 170 knots.
I agreed but told them i would require a "nonstandard" turn to final.  They agreed.  So here I am screaming in at 200 mph in a plane with a 100 mph flap speed set to make a turn to a 2 mile final.  Fun fun fun.
I was cleared to land and when the time came I chopped the throttle and rolled into a 100 degree bank with a 4G pull.  When I rolled out I was lined up with the centerline and had bled off 75 mph of speed.  I continued at about 120 kts until I was about 2000 ft from the first turn off and then dropped full flaps and put the plane into a hard forward slip.  We landed about 500 ft before the turn off (we landed on the right runway so the turn off put us between the runways) and I taxi'd tail up to the turn off.
Once clear of the runway, approach thanked me for "expediting".  He said I'd understand in about 20 seconds why he rushed me.  He told me to contact ground on point something, and I did.
About then a fully loaded 747 roared by on the runway I had just landed on.  Not 150 ft from where I sat.  We taxied to the FBO, tied down and walked to the museum.
Later that day I spoke to a friend who flies 747s for Atlas and he explained that a small behind a heavy would require 4 minutes wait for wake turbulence to clear.  With a heavy behind a small, as long as I was clear, the heavy would land.
Fun fun fun.  At the time I was flying formation aerobatics so i was on my game.  I was flying 2-3 times a week and very very proficient.  I looked at the request for a nonstandard approach as a fun challenge.  If I ever felt uncomfortable, I would simply reply "unable".
Remember, the pilot is in charge of the aircraft.  As I referenced above.  NY approach tends to vector small piston aircraft out to sea.  I had this happen to me exactly once.  When he asked me to turn even further out, I cancelled flight following and bid him a good day.  Eff him.  Ever since then I generally don't call when over NY's class Bravo.  Or if I do, I make sure I'm above 7500 so I can cancel FF if they want me to do anything I don't want to do.  I'm all for working in the system, but I will not be put in danger so that a busy controller can have an easier day.
Don

Dulles is still under the DC SFRA, which requires a flight plan with specific entry bearing and destination airport, plus squawk and talk. It's unlikely these rules will be relaxed in our lifetime.

100 degree bank? Really?

The short answer is that it depends on the airport, and on the day and time of day. Not all Class Bs are equal, and traffic density differs with the seasons and times of day.
On paper, SeaTac is fairly quiet for a class B; it sees about 945 operations a day on 3 runways (the third one being recent, opening in late 2008). The problems with the airport are in the ground facilities layout; every terminal that is the origin or destination of a flight at SeaTac is on the east side of the runway complex. That means up to 2/3 of flights require at least one runway crossing during taxi, and with a plane taking off or landing every four minutes on each runway, there's no time to dawdle. Very generous ILS holds due to the varying runway lengths further congest the usable taxiways. One GA pilot, unfamiliar with the traffic flow, can really throw a wrench in the works. As Jason Malinowski said in his answer, if you just want to touch and go they can probably get you in on the newest runway, but if you're planning on parking there you'll likely be staring up at the south end of a passenger jet for a while.
By contrast, an airport like Sky Harbor, which sees 1,200 operations a day on the same number of runways, is more efficiently laid out, with a center passenger terminal complex between the two longest runways, and most GA facilities located to the south of the complex along with cargo and ANG terminals, all conveniently next to 7R/25L (the shortest runway at 7800 feet, more or less reserved for small craft). Sky Harbor therefore tends to be a little friendlier to small singles and twins on XC flights (or just logging Bravo time for a student/rec endorsement).
DFW, larger still (1,800 ops/day), could easily be thought of as two different co-located airports with a common road system. Runway 17L/35R on the east side is specifically intended for use by GA craft including small props, with the other four primary north-south runways serving larger passenger flights (typically the inside runway on each side is for takeoffs and the outside for landings), so provided you can keep pace on the radio you're just fine flying your small prop into DFW (they discourage practice flights though). However, the winds in the area are less constant; when a front from the Gulf brings winds out of the southeast, the entire airport runs on just two auxilliary 13/31 strips. In that situation, the East Tower primarily responsible for GA all but closes to small craft, and nearby Love Field as well as the numerous Class Ds in the Metroplex (Addison, Dallas Exec, Spinks, Meacham, Alliance) see a significant uptick in small props and business jets.
O'Hare is just busy; no two ways around it. When the winds are favorable it has four runways on which to handle about 2400 flights a day (that's a plane taking off or landing from each runway every two and a half minutes on average), and when winds are out of one of the secondary compass points, each of the two usable runways will see a plane rolling down it every 75 seconds. A quick scan of the complex on Google Earth shows exactly one small twin in the entire complex, at Signature Flight Support toward the northeast. Everything else I see is at least a 50-place regional. They'll work you in if they can, as Fab's answer proves, but I'd be wary of duplicating his flight with the winds out of the southeast. Midway, closer to downtown, does seem to cater more to small props, but even then with Southwest's expanded schedule into this airport I imagine you'd be in for a fairly closely-spaced approach. As a result, I'd say if you were planning a private flight into the Chicago area, you should plan on landing at one of the class Ds, like Chicago Exec, Gary or Waukeegan.

If you go into any big airport you had better be organized and prepared. First of all be alert with you communications, ATC gives instructions once and expects you to understand what is being said and that expect you to do it, they may not have the time for seconds. The more they have to work with pilots that do not know the airport or procedures only loads the system and sets up hazard situations.
Once on the ground have an airport diagram chart open and read to use. I recommend that you have paper and pencil ready to copy a taxi clearance.
When you are at airports like LGA they do not have the normal taxiway signs, the signage is painted in the runways and taxi ways and are difficult to see when the cockpit is low to the ground. Especially when crossing runways that have crowns, Good luck in night conditions. The big airplanes with pilots that se 20 feet above the airport do not have that problem.
Other than that, no problem.

I trained out of Nashville International Airport on Cessnas.  Generally, ATC was great about finding ways to fit you in to the pattern with the commercial airliners.  Occasionally, they would ask you to circle east of the airport for a little while if they were busy, but even then, they were pretty efficient about bringing the GA planes home.  (May have helped that BNA had three parallel runways, so often they could bring the smaller planes in on the center runway without disrupting the larger jets.)

Since Seattle was mentioned in the original poster's question:
I recently asked one of the SeaTac approach controllers at a conference about this, they said they were completely fine with it. As long as you asked early enough so they can get you sequenced in, they can put you on 16R/34L and you are out of the way of other traffic. That runway is fairly new (built in 2008), and so perhaps it was more of a problem years ago when they only had two.
In some cases, they might clear you for the option instead of clearing you to land. That way, you have plausible deniability that you did land, and might get out of a landing fee.

I've flown into Chicago Midway before (as part of my IFR long XC training flight).  It was fun.  :-)
In the USA, if you're IFR they have to take you.  They can refuse VFR flights though.  However, at the ATC seminar I was at the other night, he mentioned that while they have to take IFR flights of any size, nothing says when they have to take you.  During the airline pushes you may get stuck in a hold for a couple of hours if they've already got a big stack of airliners, so it can be in your best interest to divert elsewhere, hang around on the ground until your hold time would have been up, then just hop over VFR...

IFR traffic is supposed to be handled on a first-come-first-serve basis in the US....

True in general, but major airports have IFR slot reservations during special events and other very busy times when they're at full operational capacity.  Some people are more equal than others...  :-)

Absolutely, and if a slot is required then you need to get one in advance so you will know whether or not you need one and if you don't have one then you will probably have to hold or go somewhere else.


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How can I politely remind ATC that I'm waiting for instructions or clearance?
(background: low-hour, low-experience, private pilot.)
I've got an issue regarding talking to air traffic controllers, especially when I think they may have messed up, yet still giving them the respect they deserve as hard working professionals.
One common scenario is when I'm ready to go, along with multiple other planes, all coming from various taxiways.   I know the tower tries hard to clear us each more-or-less in the order we've called up.   But when one plane feels they've been badly skipped, or possibly forgotten, it can get awkward.
I've heard a pilot say (very politely, and with good cause):

"Tower; Arrow-23: Did you forget about me?"

only to have the tower come back with a snappy and frustrated:

"I'm doing the best I can.  I'll get you all out of here as fast as I can.  Just wait your turn!"

Obviously, that didn't go very well.
On the other hand, I've tried to be patient for awhile, only to learn that the Tower really did overlook me, and sequenced several planes out in front of me.
On the ground, its wasted fuel, HOBBS, and time.
But in the air, it can be more significant.
Sometimes I've had tower miss actually clearing me to land.If they're trying to sequence me in, I stay on an extended the downwind leg for a long time, waiting to be cleared before turning base.  But if they really did get busy and overlook me, I can end up well out of position.
If I call and ask, sometimes they'll get a little testy with me if they are just busy.
If I stay silent, I might've been skipped/forgotten, and end up flying downwind for a long time.
Whats the most appropriate, friendly, and polite way to check in and make sure nothing got missed, without sounding accusatory?

Good question. Many times I have been cleared for the approach and didn't hear anything back (no landing clearance) until I've descended to 200ft. At that time I have other things on my mind than to ask if I was cleared to land or not. On the last occasion I simply went around because they didn't clear me to land. They were really upset (with themselves?) and it never happened again since :-)

If you need something, just say your callsign. The controller, thinking about other things, will be reminded about you, and if they know what you need they will likely give it to you right then.

I work at a very slow tower (two or three in the pattern at once is a notable event) so other controllers may have a different perspective, but I don't think it's a requirement for you to have a landing clearance before turning base. Certainly if you don't, you could report turning base to prompt the controller—but I expect pilots to turn a normal base unless I explicitly tell them otherwise (follow traffic, extend downwind, make short approach, etc), whether or not they have a landing clearance at the time.

There's lots of advice I can give you here, but the answer is really that the degree of communication tower wants/needs depends on your local tower (and to some degree the individual controllers).
Perhaps the most universal piece of advice I can give you is to think like a controller.  Listen to the frequency and get a picture of what's going on in the airspace before you call them, and when you get good at it you'll also get good at knowing what kind of a situation you're flying in to (Is the airspace empty, or are there 4 planes in the pattern for landings, 3 in the opposite downwind shooting touch-and-gos, and a jet arrival on an instrument approach that just got dumped on the tower inside 7 miles barreling in & messing everything up?)
Also remember that from a controller's perspective of priorities ("Safe, Orderly, Expedient") speed doesn't count for much when compared to the other two requirements of the job (and aircraft on the ground are inherently Safe and Orderly unless they do something stupid like go charging across the hold-short line). Unfortunately for us pilots delaying the plane on the ground (that isn't moving, and is thus unlikely to hit anything) is generally preferable to trying to maneuver and delay the ones in the air (that can't stop moving unless they hit something, which is generally considered to be a Bad Thing).
For a masters class in "thinking like a controller" call your local tower and ask to arrange a tour / shadow a controller for an afternoon. Spending the day in the cab is a great way to get an appreciation for how crazy things can get up there.
You can usually Google up the phone number, or call Flight Service or your local FSDO and ask. For most towers it's relatively easy to set up a tour (they'll ask for a driver's license and possibly FAA certificate number to do a background check and make sure you're not completely insane).

The rest of this post is just my personal view on getting along with controllers based on doing most of my training & flying at a pretty busy towered field (According to the FAA's ATADS "Tower Operations" ranking KFRG was #42 in 2013).

On The Ground
When you're ready to go call tower and tell them - Something like Tower, Cessna 12345 number one runway 32, ready to go. is usually plenty (if your airport is configured such that there may be some question as to where you are specify which taxiway/intersection you're at).
After you call the tower and tell them you're ready my experience is you're not likely to be forgotten about. You may be sitting there for a while (my personal record is about a half hour at the hold-short line), but the tower can usually see you sitting there at the runway end waiting. They want to get rid of you, they just need a hole big enough that they can get you onto the runway and airborne without creating any conflicts.
If you are forgotten (it does happen sometimes - you'll see other aircraft being cleared for takeoff who called the tower to report ready after you, or the controller changes, or you've been listening and are pretty sure the airspace is clear but you're still waiting) a polite call to remind the tower you're ready to go isn't out of order. Just don't be That Guy calling every couple of minutes, and if the controller gets a little snippy just be the better person and shrug it off.

In The Air
In the air is a slightly different story.  Sometimes it can take me 3 or 4 calls to get tower to even acknowledge my existence on busy days (again, you don't want to be That Guy calling the tower every 10 seconds - you should have a picture of what's going on in the airspace, and if the controller is busy you may have to circle outside their airspace for a while).
Once you've made contact a good controller will communicate with you and tell you what they need you to do and where they want you to report, where to turn base, or who they want you to follow.
If you feel like you've been forgotten a well-timed position report is usually the best way to remind the tower you exist (and as a bonus it helps everyone else with their mental picture of the airspace too).
For example on an extended downwind for runway 01 at Republic you'll pass Sunrise Highway (a pretty easily identified road, and if you miss it you'll spot the train tracks right after it), the inner shore of Long Island, and the outer shore of the barrier beaches. Reporting each of those points while waiting for tower to call your base generally works (if they genuinely forgot about you they'll usually have an "Oh S%$^!" moment when you call them over the outer shoreline and turn you in for a 7-mile final).

One exception to my position reports technique is landing clearance -- I generally do something to remind myself if I've been cleared to land (fold a chart, turn my kneeboard, etc.) and if I don't recall being cleared I'll call somewhere between 500 feet and the threshold with something line Tower, confirm N12345 landing clearance? (Where depends on the conditions of the day - sometimes they crank out departures pretty tight & if someone's rolling waiting until they're airborne is usually a good idea).
Sometimes they cleared me and I missed it.
Sometimes they didn't clear me and they do.
Sometimes they have an "Oh S%$^!" moment (they forgot about me, have a conflict, and I go around).
All of those situations are generally preferable to landing on a runway someone else may have been told they can use.

Excellent advice!

For landing clearance, what I've been doing is turning on the taxi light when cleared for the approach and the landing light when cleared for the landing.  That way you won't forget if you've been cleared or not, and you can tell right away (and you increase your lighting as you get closer to the airfield, which is always a good idea)

@Aaron - In most situations, it doesn't hurt to have the landing light on below 10000 ft anyway. It makes you much more visible to any aircraft operating VFR (or in VMC conditions), and it isn't used just for takeoffs and landings.

I generally just use the taxi light in those situations (since I don't fly IFR), on the premise that you point out, and the taxi instead of the landing light because I would prefer to have the landing light instead of the taxi light if it burns out...

Awesome answer.  I shadowed a Memphis Center controller for a couple of hours and gained a lot of respect (not that I didn't have any before) for what they do.  I have also been inside Memphis TRACON, and the level of tension is an order of magnitude greater at any given time.  Can't imagine what the Tower is like when 150 FedEx jets are bearing down trying to land in a 45 minute window.

Great advice. At KPAO common in the local dialect in its busy airspace is “N12345 sequence please”. This way, even if you’ve been told already, they can update you on who is left in the pattern.

What I usually do is repeat the last clearance or instruction. That way you give ATC the impression that you're not impatient but just reporting your progress. If they really forgot you they will quickly rectify the situation. If they didn't and it was intentional, they won't feel as if they are being accused.
Examples:
When holding at a holding point:

Tower, N1234, holding RWY 27

When still on extended downwind, being "forgotten":

Tower, N1234, continuing downwind

When waiting for a landing clearance during approach:

Tower, N1234, continuing approach

And if they still don't clear you when you're already below 200ft or over the threshold:

N1234, VERY short final

I think that your last example is a little too vague.  Sometimes it pays to be specific, such as when faced with an imminent go-around: "Tower, please confirm that N1234 is cleared to land", even if you aren't, tells them exactly what you are looking for and even an "out": "Affirmative,  N1234 cleared to land runway 8".  If they think that they have already cleared you, they may not come back with a landing clearance at that point and you week end up going around.

I used to do that but I got tired of it because it was happening so frequently so I started saying "very short final", stressing the word "VERY". The last time I simply went around, messing up their sequencing and it never happened again.

Well, when flying jet airplanes that go-around can cost a whole lot more than I think is worth the satisfaction gained by messing up their sequencing.  :-)

Getting distracted by a last-second landing clearance can cost even more, and not just in money.

Hence not waiting until the last second....

Yes, exactly, and that's why it's so annoying. IMHO, it's unacceptable for a controller to forget about the landing clearance when on short final. It shouldn't be something that the pilot should have to worry about while landing. I get nervous when I haven't been cleared to land (because the controller forgot about it). When I'm nervous I make bad landings, and I think I'm not the only one.

let us continue this discussion in chat

Lots of good feedback here.  Whenever I am compelled to call the ATC to confirm a clearance or instruction, or if I suspect I was simply forgotten, I just carefully word it as though I may be the one who missed their call even if I'm 99% certain I didn't.
For example, I'd never say, "Tower N1234 sitting at the threshold of 27 ... did you forget about me?"  (Accusative)
Rather, "Tower N1234 sitting at the threshold of 27 ... did I miss your clearance for takeoff by chance?"  (Inquisitive)
Many towered airports ... especially Class Delta ... have their own little methods of madness or traditions or idiosyncrasies that you won't know the first or second time in.  I recently flew in and out of Fort Myers Page Field.  Normally, I'll never switch from ground to tower until told to do so.  I taxied to the runway threshold, did a runup, then called ground to say I was ready to go ... and "Shall I switch to the tower frequency?"
Answer, "N1234, at this airport, whenever you arrive at the threshold you may go ahead and switch to the tower frequency and let 'em know when you're ready."
OK ... fine ... cordial ... polite ... but certainly not by the book.

I fly in and out of FMY Page quite a bit also. Calling Tower (local) is standard procedure at most facilities in the United States (per the AIM, 4-3-14) There are exceptions to the procedure listed below: APA (Centenial Airport in Denver) broadcasts on the ATIS to let Ground Control know when you are ready for departure rather than the tower. This is also done at several large airports with numerous tower frequencies.


text:
What licenses / permits are required to perform slingload operations in a helicopter?
Regulation-wise, what is needed to conduct slingload operations in helicopters in the USA?
I would like to know regulations about both the aircraft and the pilot.

It's not a common topic for general airmanship in helicopters.  Most likely it's part of a type rating for a large helicopter designed for that sort of stuff.

This one I found in the FAA Helicopter Instructor's Handbook
In the United States, FAR Part 133 covers this.  For the Flight Crew, you are required to obtain either a commercial or airline transport pilot certificate - rotorcraft helicopter with additional ratings for external load carriage.  This rating can be obtained only at the behest of the chief pilot licensed for external loads and under the employ of an operator holding an external loads certificate and requires both a knowledge test and a practical test as prescribed in Part 133.
The helicopter in question must hold a valid restricted category airworthiness certificate and must have been designated for the carriage of external loads on its type certificate or by STC per Parts  21, 27 and 29.
The operator must hold a current Rotorcraft Helicopter External Load operator's certificate which must be renewed every 24 calendar months.


text:
Are there any ILS approaches in Class E airspace?
When descending on an ILS you can descend to 100' above the TDZE if you have the approach lighting system in sight. Cody Johnson wrote an article explaining how one pilot mis-interpreted what the rules allowed him to do, descended below 100' when there were obstructions in the way and crashed into a hill. (https://iflyamerica.org/misunderstanging_part91.asp )
Section 91.129(e)(3), Operations in Class D Airspace, is also extremely applicable in this accident. It says, 'An airplane approaching to land on a runway served by a visual approach slope indicator shall maintain an altitude at or above the glide slope until a lower altitude is necessary for safe landing.'
Class C and B incorporate Section 91.129(e)(3) by reference, so the rule applies in that airspace as well. It doesn’t specifically apply to operations at airports in Class E airspace.
My question is are there any ILS approaches in Class E airspace? Is there a a rule that prohibits them, or conversely, only allows them when there is a tower?

Visalia, CA (KVIS) is an uncontrolled airport with a Class E surface area and an ILS with 200' minimums.

Now that I know that there are some, I wonder why the descent rule doesn’t apply to them.

ILS approaches are even possible in Airspace G.

@pcfreakxx please name one. I ask because the FAA has ruled that IFR is Class G is illegal (see https://www.faa.gov/about/office_org/headquarters_offices/agc/pol_adjudication/agc200/interpretations/data/interps/2016/Lamb%20-%20(2016)%20Legal%20Interpretation.pdf)

@SteveKuo -- no, IFR in G without a clearance is illegal.

@SteveKuo Actually you need a RMZ (or airspace F). One example is EDGS aerodrome.

@Steve Kuo That letter specifically says that the FAR's are silent on the issue. The issue is addressed in this question. The example given is where the pilot took off into IMC from uncontrolled airspace when ATC refused clearance. They could not provide separation and IMC meant he couldn't see-and-avoid so they said it was reckless to take off without clearance.

@pcfreakxx RMZ and class F don't exist under FAA

@TomMcW But they do exist according to ICAO

@pcfreakxx -- member states are free to have documented variances from ICAO's rules

@UnrecognizedFallingObject Did I say anything else?? NO! But my example was EDGS which is in germany and therefore regulated by ICAO

@pcfreakxx -- we're trying to point out that pointing out a German example isn't really relevant on a question tagged [faa-regulations] m8

@SteveKuo ILS 7 to LPR. The ILS takes you down to 200' AGL, but class E ends at 700 AGL.

@UnrecognizedFallingObject ('s first comment): IFR anywhere without a clearance is illegal.

@SteveKuo -- re"@pcfreakxx please name one."-- an example is KCVO-- see https://flightaware.com/resources/airport/KCVO/IAP/all/pdf

There are plenty of ILS approaches in Class E surface area (e.g. KCLM, KHQM, KPWT). In fact the presence of an ILS will usually require that some kind of controlled airspace extends to the surface. For an untowered airport this means a Class E surface area.

Around airports, instrument approaches are what class E is all about. That's what results in the "keyhole" shape of class E 700ft and surface area extensions.
Class E surface area surrounding an airport is usually used for airports that do not have a tower or at times when the tower is not operating.

From AIM 3-2-6 §e.1. Surface area designated for an airport where a control tower is not in operation. Class E surface areas extend upward from the surface to a designated altitude, or to the adjacent or overlying controlled airspace. The airspace will be configured to contain all instrument procedures.

(a) To qualify for a Class E surface area, the airport must have weather observation and reporting capability, and communications capability must exist with aircraft down to the runway surface.1
(b) A Class E surface area may also be designated to accommodate part-time operations at a Class C or Class D airspace location (for example, those periods when the control tower is not in operation).

But Class E extensions are also used to protect approaches to towered airports in B,C, or D areas.

AIM 3-2-6 §e.2. Extension to a surface area. Class E airspace may be designated as extensions to Class B, Class C, Class D, and Class E surface areas. Class E airspace extensions begin at the surface and extend up to the overlying controlled airspace. The extensions provide controlled airspace to contain standard instrument approach procedures without imposing a communications requirement on pilots operating under VFR. Surface area arrival extensions become part of the surface area and are in effect during the same times as the surface area.1

Anywhere there are instrument approaches not protected by class B, C, or D airspace you can expect a class E extension. Anywhere aircraft on approach are expected to go below 1000 feet there will usually be a class E surface extension.2
1FAA Aeronautical Information Manual[PDF]
2 Russ Roslewski, How are Class E surface area extensions determined?

KPNE has an ILS for their 24 runway they are class D airspace between 1100-0400Z and class E all other times. The approach, as far as I know, remains on while the airport is class E.


text:
How hard is it to fly a US-registered private jet over Cuba?
I know that commercial airlines have airspace passage agreements that allow them to fly over Cuba, but what about private jets? Is it easy for a pilot of a US-registered private jet departing from Miami to get an overflight clearance from Cuba? What is the procedure?
I am specifically asking about an overflight, not a landing. In other words the pilot wants to fly over Cuba en route to some other destination in South America.